Microsoft claims that there's no problems with its "Consider replacing your battery." warnings, which it defended in a lengthy blog post. Many customers say otherwise, complaining that the OS is reporting brand new batteries to be failing. (Source: Microsoft)

Users unsatisfied with Microsoft's response

Laptops
now outnumber desktops in sales and that trend is only set to broaden
in coming years. With the majority of customers now using
laptops, anything on an operating system level that affects laptop
users is becoming increasingly important. Thus, when reports
popped up that Windows 7 was erroneously telling users to replace
their batteries on perfectly healthy notebooks, many took
note.

Microsoft's Windows President, Steven Sinofksy, has
fired back in a long post in which he defends how things currently
work, stating that his staff have found no bugs. He writes,
"One of the most obvious components of PC battery life (the
runtime you get on battery power) is the battery itself. PC batteries
inherently degrade in their ability to hold a charge and provide
power (as is the case for all rechargeable batteries). The cause of
this is complex and includes irreversible changes in battery
chemistry, and increased internal resistance among other things and
those in turn are dependent on the design and manufacturing of the
battery. This degradation translates into less battery life for the
user over the life of the battery in the PC. Ultimately,
batteries must be replaced to restore an acceptable battery
life."

Mr. Sinofsky says that it warns users to change
their battery whenever it is operating at less than 60 percent of its
original capacity in watt hours. He explains how this works,
writing:

PC
batteries expose information about battery capacity and health
through the system firmware (or BIOS). There is a detailed
specification for the firmware interface (ACPI), but at the most
basic level, the hardware platform and firmware provide a number
of read-only fields that describe the
battery and its status. The firmware provides information on
the battery including manufacturer, serial number, design
capacity and last full charge capacity. The last two
pieces of information—design capacity and last full charge
capacity—are the information Windows 7 uses to determine how much
the battery has naturally degraded. This information is
read-only and there is no way for Windows 7 or any other OS to write,
set or configure battery status information. In fact all of the
battery actions of charging and discharging are completely controlled
by the battery hardware. Windows only reports the battery
information it reads from the system firmware. Some reports
erroneously claimed Windows was modifying this information, which is
definitely not possible.

Despite
this assurance, though, many customers still say Windows 7 is saying
they need to replace their battery on new machines or machines with
little battery wear. The response section of the blog was
inundated with angry replies from users experiencing such
issues.

Among the models that reportedly have had
this problem are the Asus
Eee PC and certain Acer Aspire models. Some users have
reported that Windows 7 is shutting down their computers when they
still have battery life remaining. And other users have noted
that they can take the "failed" battery and put it in a
non-Windows 7 machine and it will charge just fine.

Given the
amount of complaints and uncertainty, Microsoft hopefully is
investigating this issue further, however, it clearly appears to
currently feel that there's no issue at all, despite its customers'
testimonies.